The present invention relates to co-generation power systems, for example, solar photovoltaic or wind-power, connected to non-dedicated branch circuits in a residential or commercial setting. Specifically, the application relates to a safety device for adjusting the current flowing into a non-dedicated branch circuit from a co-generation device.
Utility-interactive solar power or wind power co-generation systems of various sizes are commonly installed on homes and businesses, but implementation can be cumbersome. For example, solar photovoltaic panels and utility-interactive inverters are available and may be configured as effective and safe power generation systems whereby a home may be powered by a combination of utility and solar-generated electricity. However, these systems require installation of a properly sized and dedicated branch circuit or separate electrical service in order to safely add solar generating capacity to a home.
With the use of small co-generation system in a residential or office setting, it may be desirable to supply power from the co-generation system into an existing branch circuit using existing wiring. For example, it may be desirable to supply power from a solar or wind-power co-generation system or device into an existing electrical outlet or receptacle already present in a home or business.
It is common in residential and commercial wiring, to have non-dedicated or general branch circuits. A non-dedicated branch circuit can have several outlets or receptacles, each receptacle capable of supplying power to different devices or loads. Branch circuits originate at an electrical service panel or breaker box. Electricity is supplied from the power utility into the branch circuit through a circuit protection device, typically a circuit breaker. The breaker prevents the flow of current from the power utility into the branch circuit when the current required by one or more loads on the branch exceeds the rated current capacity of the branch circuit. However, when a co-generation system also supplies power into a non-dedicated branch circuit, the current from the co-generation system can flow directly through the branch circuit to the load and bypass the circuit breaker. This creates the potentially dangerous situation where the combination of utility supplied current and co-generation system supplied current together exceed the current capacity of the branch circuit.
While systems have been proposed that connect small residential and commercial PV solar and wind power systems through AC outlets or receptacles, none have adequately addressed the problem that the rated current capacity of a non-dedicated branch circuit can be exceeded when one or more loads are connected to the branch circuit. Therefore, the need exists to provide a device that prevents current overload in a non-dedicated branch circuit supplied by both utility power and a co-generation device.